Elephants have shorter lives in zoos, researchers find

BILL MURPHY, Copyright 2008 Houston Chronicle |
December 11, 2008

Mac was a popular elephant at the Houston Zoo before he died last month.

Elephants in zoos generally live much shorter lives than those in the wild and less restrictive settings, possibly because they are more prone to stress and obesity, a research team found.

The average lifespan of African female elephants in zoos is 17 years, while the lifespan for African female elephants in the wild is 36 years, according to a study published today in the journal Science.

The lifespan for Asian female zoo elephants was 19 years, while those working in Burma in the timber industry had a lifespan of 42 years, the study concluded.

Even though the study was published in Science, a well-respected journal, a Houston Zoo official and a spokesman for a zoo association assailed its methodology and findings.

Houston Zoo director Rick Barongi said in an e-mail that the study was unreliable because it examined only elephants in European zoos, not those in North American facilities.

"The data clearly cannot be said to reflect the situation in North American zoos," he wrote. "Zoos accredited by the Association of Zoos and Aquariums, such as the Houston Zoo, operate under a set of elephant-specific standards and guidelines that do not apply to zoos outside of North America."

Critical report

After the elephant Mac died at the Houston Zoo last month, members of groups working to protect elephants and animal welfare activists called on the zoo to stop its elephant breeding program.

None of the eight elephants born at the zoo in the past 25 years has survived. Six have been killed by the elephant herpes virus, prompting another scientific research team to characterize the zoo as a "hot spot" for the virus. Asian elephants are the only species of elephants kept at the zoo.

Among the issues raised by the spate of deaths at the zoo and others elsewhere is whether captivity plays a role in the virus' transmission and onset of illness.

Also critic of the report in Science was Paul Boyle, vice president of conservation and education at the Association of Zoos and Aquariums. "The study has virtually nothing to do with North America," he said.

Boyle noted that an earlier study concluded that the average lifespan of an Asian elephant in a North American zoo was from 36 to 45 years — about the same as the 42-year lifespan for Asian elephants working in the Burmese timber industry.

Flawed findings claimed

Clubb said that the earlier study was flawed and concluded a higher than actual lifespan of the Asian elephant in North Americans zoos.

The flaw resulted from the study's failure to include elephants that died before they turned 1.

The study found that transferring Asian elephants away from their mothers shortens their lifespans.

Three of the elephants born at the Houston Zoo died from the herpes virus after they were transferred to zoos in Berlin, Chicago and Canada.

Clubb said zoos whose calves are dying should suspend breeding programs until a cure for the herpes virus is found.

The study concluded that the lifespan for wild African elephants was 56 years when deaths of those killed by people weren't considered.

It was based on an analysis of the lifespan of 4,500 zoo and wild elephants. Wild African elephants were from the Amboseli National Park in Kenya.

Shortened lives

Among the causes of shortened lives for zoo elephants are inactivity, tuberculosis and infanticide — mother elephants in zoos are more likely to kill their calves, the study said.

Zoo elephants also have a much greater tendency to engage in repetitive movements that may be signs of less than healthy mental states, such as pacing in a circle, swaying from side to side, bobbing their heads, Clubb said.

"These behaviors have been compared to mental illness in people," she said.

Elephants walk about 7 miles a day, Clubb said. They and other animals that range miles for food, such as polar bears, are among those most prone to engage in pacing and other repetitive behaviors when captive, Clubb said.

"We need to consider whether some species can't be kept very well in zoos," she said.